Fringe syntax and duckdb syntax

[AdityaHegde]

Hi,
I am working on a query visualisation and data transformation tool where we use duckdb for profiling source table/query.

I am planning to add some deeper insights for subqueries and this library is perfect for parsing. However there are some fringe syntax missing.

I added sampling support in my fork https://github.com/AdityaHegde/pgsql-ast-parser
I am looking at adding interval operator : https://duckdb.org/docs/sql/data_types/interval

While it makes sense to have a fork for duckdb specific syntax some common syntax supported in pgsql also. It might make sense for me to raise a PR to this repo itself. Lemme know if this is fine and I can raise a PR for my changes.